Method for manufacturing silicide and semiconductor with the silicide

ABSTRACT

The present invention is directed to a method of manufacturing silicide used to reduce a contact resistance at a contact of a semiconductor device and a semiconductor device with the silicide manufactured by the same method. The method comprises the steps of: (a) cleaning a semiconductor substrate with a transistor formed thereon, the transistor including a source electrode, a drain electrode and a gate electrode; (b) placing the cleaned semiconductor substrate into a sputter chamber in a deposition equipment, and forming silicide at the same time of depositing a metal film under a state where the semiconductor substrate is heated at a temperature of 450-600° C.; (c) removing residual metal film not used for the formation of silicide; and (d) annealing the semiconductor substrate. According to the present invention, since silicide is formed at the same time of depositing a cobalt film, there is an advantage of omission of a protection film formation process over the prior arts where silicide is formed by a post-heat treatment.

BACKGROUND OF THE INVENTION

[0001] (a) Field of the Invention

[0002] The present invention relates to a semiconductor device and amethod of manufacturing the same, and more particularly to a method ofmanufacturing silicide used to reduce a contact resistance at a contactof a semiconductor device and a semiconductor device with the silicidemanufactured by the same method.

[0003] (b) Description of the Related Art

[0004] In general, a semiconductor device includes a plurality oftransistors, each of which includes a source/drain electrode and a gateelectrode in each of device regions separated from one another by adevice isolation method such as a LOCOS (local oxidation of silicon) orSTI (swallow trench isolation) method, and titanium silicide or cobaltsilicide used to reduce a contact resistance of a transistor drivingcircuit.

[0005] Techniques related to the silicide formation process aredisclosed in U.S. Pat. Nos. 6,534,390, 6,316,362, 6,013,566, 5,869,397,and 5,780,350

[0006] Hereinafter, a method of manufacturing the silicide according tothe prior arts is in brief described with reference to FIG. 3 asfollows.

[0007] First, as shown in FIG. 3A, a transistor 104 including asource/drain electrode 104 a and a gate electrode 104 b is formedbetween two device isolation regions 102 of a semiconductor substrate100, and then a cleaning process for removing a variety of undesiredimpurities such as metal impurities, organic contaminations or naturaloxide films residual on the semiconductor substrate 100 is performed.

[0008] Here, a chemical cleaning process to use SC1 (standard cleaning:an organic mixture where NH₄OH:H₂O₂:H₂O is 1:4:20) solution and HF orDHF (dilute HF) solution is used as the cleaning process.

[0009] Next, as shown in FIG. 3B, a metal film 106 is formed bysputtering metal, such as cobalt for forming silicide in a sputterchamber in a sputter system, on the entire surface of the semiconductorsubstrate 10. At this time, the semiconductor substrate 100 is heated ata temperature of 20-50° C. After forming the metal film 106, a Ti or TiNprotection film 108 for preventing nitrification or contamination of themetal film 106 in the course of a post-heat treatment process isdeposited.

[0010] Next, as shown in FIGS. 3C and 3D, silicide 110 is formed bypicking and placing the semiconductor substrate 100 into a RTP (rapidthermal process) equipment or an electric furnace and then post-heattreating it at a temperature of 400-600° C. Subsequently, after removingresidual metal film 106 not used for the formation of the silicide 100,silicide 110 with a low resistance is completed by annealing thesemiconductor substrate 100 and stabilizing a phase of the silicide 100.

[0011] However, in the prior arts as described above, since the silicide110 is formed through the post-heat treatment process and the protectionfilm 108 for protecting a surface of the metal film 106 at the time ofthe formation of the silicide 110 has to be formed, there is a problemof increase of process time.

SUMMARY OF THE INVENTION

[0012] In considerations of the above problem, it is an object of thepresent invention to provide a method of manufacturing silicide by whichsilicide is formed at the same time of depositing a metal film.

[0013] It is another object of the present invention to provide asemiconductor device with the silicide manufactured by the method of thepresent invention.

[0014] To achieve the objects, according to an aspect of the presentinvention, a method of manufacturing silicide comprises the steps of:

[0015] (a) cleaning a semiconductor substrate with a transistor formedthereon, the transistor including a source electrode, a drain electrodeand a gate electrode;

[0016] (b) placing the cleaned semiconductor substrate into a sputterchamber in a deposition equipment, and forming silicide at the same timeof depositing a metal film under a state where the semiconductorsubstrate is heated at a temperature of 450-600° C.;

[0017] (c) removing residual metal film not used for the formation ofsilicide; and

[0018] (d) annealing the semiconductor substrate.

[0019] Preferably, in the step (b), silicide with a composition ratio ofCoSi is formed, and the step (a) includes a first cleaning step ofcleaning the semiconductor substrate using SC1 solution, a secondcleaning step of cleaning the semiconductor substrate using HF or DHFsolution, and a third cleaning step of plasma-etching the semiconductorsubstrate in the sputter chamber.

[0020] Preferably, the third cleaning step using the plasma-etchingincludes a first etching step using RF power of 60-90 W and a secondetching step of RF power of 250-350 W, and uses argon gas of 3-8 sccm.

[0021] Preferably, in the step (b), the metal film is formed by using acobalt sputter with DC power of 2-10 kW, argon gas of 40-70 sccm is usedas gas for a sputtering process, and argon gas of 8-15 sccm is used asgas for heating the semiconductor.

[0022] Preferably, the step (c) includes a first removal step ofremoving the metal film during 5-15 minutes in SPM solution at atemperature of 50-150° C. and a second removal step of removing themetal film during 3-10 minutes in SC1 solution at a temperature of40-70° C., and the step (d) includes heating the semiconductor substrateduring 10-60 seconds at a temperature of 700-950° C. in a RTP equipmentor heating the semiconductor substrate during 20-60 minutes at atemperature of 500-900° C. in an electric furnace.

[0023] According to another aspect of the present invention, asemiconductor device with the silicide manufactured by the method of thepresent invention comprises:

[0024] a semiconductor substrate including device isolation regions;

[0025] transistors provided in respective device regions of thesemiconductor substrate, each of the transistors including a gateelectrode, a source electrode and a drain electrode;

[0026] a PMD (pre-metal dielectric) provided on the semiconductorsubstrate, the PMD including contact holes to expose a portion ofregions of the gate, source and drain electrodes;

[0027] contacts provided within the contact holes;

[0028] metal wire layers provided on the PMD and connected to thecontacts; and

[0029] silicide with a composition of CoSi₂ provided in the transistorsso that contact resistances of the contacts are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate an embodiment of theinvention, and, together with the description, serve to explain theprinciples of the invention:

[0031]FIG. 1 is a schematic view showing a structure of a semiconductordevice according to the present invention;

[0032]FIGS. 2A to 2G are views showing a process for manufacturingsilicide according to the present invention; and

[0033]FIGS. 3A to 3D are views showing a process for silicide accordingto the prior arts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] A preferred embodiment of the present invention will now bedescribed in detail with reference to the accompanying drawings.

[0035]FIG. 1 is a schematic view showing a structure of a semiconductordevice according to the present invention.

[0036] As can be seen from FIG. 1, in a semiconductor device of thepresent invention, a trench (not shown) is formed in a device isolationregion of a semiconductor substrate 10, and an insulation oxide film 12for isolating devices is formed in the trench. A gate oxide film 14 anda gate poly 16 are formed in a device region of the semiconductorsubstrate 10 and a spacer 18 consisting of an insulation film is formedat side walls of both of the gate oxide film 14 and the gate poly 16. Inaddition, a source/drain electrode 20 in which impurities with highconcentration and with conductivity opposite to that of semiconductorsubstrate 10 are buried is formed in the semiconductor substrate 10below the gate oxide film 14.

[0037] In addition, A PMD (pre-metal dielectric) 24 having contact holes(not shown) to expose a portion of regions of the gate poly 16 and thesource/drains electrode 20 is formed on the semiconductor substrate 10where a MOS transistor 22 including the gate oxide 14, the gate ploy 16and the source/drain electrode 20. Contacts 26 are formed within thecontact holes of the PMD 24 and a metal wire layer 28 connected to thecontacts 26 is formed on the PMD 24.

[0038] In addition, silicide 30 with a composition of CoSi₂ to reduce acontact resistance is formed on the gate poly 16 to contact with thecontacts 26 and on the source/drain electrode 20.

[0039] Hereinafter, a method of manufacturing the silicide 30 is will bedescribed as below with reference to FIG. 2.

[0040] First, as shown in FIG. 2A, the transistor 22 including thesource/drain electrode 20 and the gate electrode 14 and 16 is formed onthe semiconductor 10 and then a cleaning process for removing a varietyof undesired impurities such as metal impurities, organic contaminationsor natural oxide films residual on the semiconductor substrate 10 isperformed.

[0041] In this embodiment, the cleaning process includes a firstcleaning step of cleaning the semiconductor substrate 10 using SC1(standard cleaning: an organic mixture where NH₄OH:H₂O₂:H₂O is 1:4:20)solution, as shown in FIG. 2B, a second cleaning step of cleaning thesemiconductor substrate 10 using HF or DHF (dilute HF) solution, asshown in FIG. 2C, and a third cleaning step of plasma-etching thesemiconductor substrate 10, as shown in FIG. 2d. However, these stepsare merely exemplified, not requisite for the present invention.

[0042] At this time, the third cleaning step as shown in FIG. 2D isperformed in a sputter chamber (not shown) of a sputter system for metalfilm deposition, and argon gas of 3-8 sccm is used as a source ofplasma.

[0043] In addition, the plasma-etching is preferable to include a firstetching step using RF power of 60-90 W and a second etching step of RFpower of 250-350 W.

[0044] Subsequently, as shown in FIG. 2E, a metal film 32 is formed bysputtering metal, such as cobalt and titanium for forming silicide inthe sputter chamber, on an entire surface of the semiconductor substrate10. Hereinafter, the metal film 32 consisting of a cobalt film will bedescribed as an example.

[0045] Then, the semiconductor substrate 10 is heated at a temperatureof 450-600° C. using a heater block (not shown) or a convection currentby argon gas. In the case of the convection current, argon gas of 8-15sccm can be used as gas for heating the semiconductor 10.

[0046] Next, under a state where the semiconductor substrate 10 isheated at the temperature of 450-600° C., the cobalt film 32 isdeposited by a sputtering method. At this time, when sputtered cobaltatomics reach the substrate 10, thermal energy by the temperature of thesubstrate 10 is transferred to the sputtered cobalt atomics. Silicide 30with a composition of CoSi is formed at a surface at which the sputteredcobalt atomics collide with silicon, as shown in FIG. 2f. At this time,it should be understood that the cobalt film deposited on the insulationoxide film 12 or the spacer 18 is not silicified even when thermalenergy is transferred to the cobalt film 32. That is, self alignedsilicide is formed at the same time of depositing the cobalt film 32.

[0047] However, if the temperature of the substrate 10 is high, since abarrier to impede the formation of the cobalt silicide 30 is formed on asilicon surface to which thermal energy is transferred, silicificationis not effectively achieved.

[0048] To avoid this, when cobalt is sputtered, the cobalt film 32 isformed by using a cobalt sputter with high power, preferably, DC powerof 2-10 kW, and gas for low pressure process, e.g., argon gas of 40-70sccm. The cobalt atomics sputtered from the cobalt sputter with highpower can penetrate the barrier formed by thermal energy so that thesilicide 30 can be formed.

[0049] Next, as shown in FIG. 2G, after removing residual metal film 32not used for the formation of the silicide 30′, the silicide 30 with acomposition of CoSi₂ having a low resistance is completed by annealingthe semiconductor substrate 10 and stabilizing a phase of the silicide30′. Here, the cobalt film 32 can be removed by a first removal step ofremoving the metal film during 5-15 minutes in SPM solution at atemperature of 50-150° C. and a second removal step of removing themetal film during 3-10 minutes in SC1 solution at a temperature of40-70° C.

[0050] Here, the annealing can be achieved by heating the semiconductorsubstrate 10 during 10-60 seconds at a temperature of 700-950° C. in aRTP equipment or heating the semiconductor substrate 10 during 20-60minutes at a temperature of 500-900° C. in an electric furnace.

[0051] As apparent from the above description, according to the presentinvention, since silicide is formed at the same time of depositing acobalt film, there is an advantage of omission of a protection filmformation process over the prior arts where silicide is formed by apost-heat treatment.

[0052] Although a preferred embodiment of the present invention has beendescribed in detail hereinabove, it should be clearly understood thatmany variations and/or modifications of the basic inventive conceptsherein taught which may appear to those skilled in the present art willstill fall within the spirit and scope of the present invention, asdefined in the appended claims.

What is claimed is:
 1. A method of manufacturing silicide, comprisingthe steps of: (a) cleaning a semiconductor substrate with a transistorformed thereon, the transistor including a source electrode, a drainelectrode and a gate electrode; (b) placing the cleaned semiconductorsubstrate into a sputter chamber in a deposition equipment, and formingsilicide at the same time of depositing a metal film under a state wherethe semiconductor substrate is heated at a temperature of 450-600° C.;(c) removing residual metal film not used for the formation of silicide;and (d) annealing the semiconductor substrate.
 2. The method of claim 1,wherein, in the step (b), silicide with a composition ratio of CoSi isformed.
 3. The method of claim 2, wherein the step (a) includes a firstcleaning step of cleaning the semiconductor substrate using SC1solution.
 4. The method of claim 3, wherein the step (a) furtherincludes a second cleaning step of cleaning the semiconductor substrateusing HF or DHF solution.
 5. The method of claim 1, wherein the step (a)further includes a third cleaning step of plasma-etching thesemiconductor substrate in the sputter chamber.
 6. The method of claim5, wherein the third cleaning step includes a first etching step usingRF power of 60-90 W and a second etching step of RF power of 250-350 W.7. The method of claim 5, wherein the third cleaning step uses argon gasof 8-15 sccm.
 8. The method of claim 2, wherein, in the step (b), thesemiconductor substrate is heated at a temperature of 450-600° C.
 9. Themethod of claim 8, wherein, in the step (b), the metal film is formed byusing a cobalt sputter with DC power of 2-10 kW.
 10. The method of claim8, wherein, in the step (b), argon gas of 40-70 sccm is used as gas fora sputtering process, and argon gas of 8-15 sccm is used as gas forheating the semiconductor.
 11. The method of claim 2, wherein the step(c) includes a first removal step of removing the metal film during 5-15minutes in SPM solution at a temperature of 50-150° C. and a secondremoval step of removing the metal film during 3-10 minutes in SC1solution at a temperature of 40-70° C.
 12. The method of claim 2,wherein the step (d) includes heating the semiconductor substrate during10-60 seconds at a temperature of 700-950° C. in a RTP equipment. 13.The method of claim 2, wherein the step (d) includes heating thesemiconductor substrate during 20-60 minutes at a temperature of500-900° C. in an electric furnace.
 14. The method of claim 2, wherein,the silicide annealed in the step (d) comprises a composition of CoSi₂.15. A semiconductor device with the silicide manufactured according toany one of the preceding claims 1 to 13, comprising: a semiconductorsubstrate including device isolation regions; transistors provided inrespective device regions of the semiconductor substrate, each of thetransistors including a gate electrode, a source electrode and a drainelectrode; a PMD (pre-metal dielectric) provided on the semiconductorsubstrate, the PMD including contact holes to expose a portion ofregions of the gate, source and drain electrodes; contacts providedwithin the contact holes; metal wire layers provided on the PMD andconnected to the contacts; and silicide with a composition of CoSi₂provided in the transistors so that contact resistances of the contactsare reduced.
 16. The semiconductor device of claim 15, wherein thesilicide comprises a composition of CoSi₂.